Hidden iOS 27 Code Shows Siri AI Can Be Replaced by ChatGPT or Claude [Video]

Hidden code in iOS 27 and macOS Golden Gate shows Apple built its new Siri architecture so third-party AI models can take on roles normally handled by Apple's own models, including replacing its server-side Siri model entirely. Developer pdfu uncovered the private frameworks and demonstrated two different mechanisms working with Claude and GPT-5.6 Terra in videos shared on X.



The first uses the Model Delegation API in App Intents. In the demonstration, Claude appears as a Siri extension through the same underlying flow as Apple's built-in ChatGPT extension, showing up in Siri's "Ask…" menu. Asked to set a reminder, Claude interprets the natural-language request and relays it back to Siri, which creates the item in Reminders.


The extension can also handle requests Siri cannot complete on its own. In another example, Claude is asked to create a CSV file and returns it inside the Siri interface. Responses are identified with a Claude label but otherwise use the standard Siri AI presentation. The mechanism requires Apple's private com.apple.developer.model-delegation entitlement, suggesting Siri could retain control over system interactions while an outside model handles the delegated request.

iOS 27 and macOS Golden Gate have private hooks that let apps add Siri Extensions and replace Siri AI's server backend with third-party models.

First, here's Claude running as a Siri Extension using the Model Delegation API in App Intents. Claude can appear in Siri's "Ask…"… pic.twitter.com/OXKHQ4hDY8

— pdfu (@itspdfu) September 13, 2026

A second protocol goes considerably further. An inference provider in Model Manager Services can replace Apple's server-side Siri model with another model, demonstrated by pdfu using GPT-5.6 Terra. In that configuration, GPT-5.6 receives Apple's native Siri planner prompt and tool definitions, allowing it to call Siri tools, request system actions, and work with the results those tools return, including personal data.


The demonstration shows GPT-5.6 finding emails about a particular topic, summarizing their contents and action points, and then sending a message through the Messages app. Its activity is also logged in OpenAI's platform web interface, while the final answer is presented through Siri's own interface and voice. Both demonstrations appear to have been performed on a Mac.

None of this is enabled for users yet. The "Ask…" implementation currently supports only ChatGPT in the Release Candidate of macOS Golden Gate, which Apple is set to release on September 14. Claude is not available as a user-facing option, and Apple has not opened the Model Delegation entitlement to third-party developers.

For now, the frameworks reveal what Apple's new Siri architecture is capable of, not what the company will ultimately make available. Apple has not announced whether third-party developers will receive access to either mechanism or whether users will be able to choose their preferred AI provider.

And here's an app extension replacing Siri AI's server model with GPT-5.6 Terra. It uses the Inference Providing protocol in Model Manager Services.

GPT-5.6 receives Apple's native Siri planner prompt and tool definitions. It can make tool calls that perform system actions, and… pic.twitter.com/cz88kyq3io

— pdfu (@itspdfu) September 13, 2026